Power-saving voltage converter operation

ABSTRACT

Whether a connector element electrically connected to a direct-current output of a converter that converts alternating current into direct current is connected to an external device may be detected. The converter may be disabled in response to the electrical connector component not being connected to the external device. In response to the electrical connector component being connected to the external device, the converter may be enabled.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.13/348,987, filed Jan. 12, 2012, which is incorporated herein byreference in its entirety for all purposes.

BACKGROUND

The present invention relates to the field of power supplies, and morespecifically, to reducing power consumption in power supplies forelectronic devices requiring a non-commercial voltage supply, as istypical of mobile electronic products.

Individuals and corporations are becoming increasingly aware of theirenergy consumption and are actively seeking to reduce it. Whether theprimary motivation is to reduce the size of a carbon footprint or saveon energy costs, consumers are demanding more energy efficient andeco-friendly products from manufacturers. In our age of ubiquitouselectronic devices, consumers and regulators are becoming increasinglyaware of the energy costs of electronics. A common culprit of energyinefficiency is the so-called energy vampire. Common electrical devices,such as computers, televisions, and appliances require standby power andconsume electricity even when the device is off. Standby power accountsfor the power necessary to allow the device to maintain information evenwhen it is off, respond to remote controls, or provide other functions.It also accounts for parasitic losses in the device. The power consumedin standby mode is comparable to the power consumed in active mode formany devices.

Many devices, such as laptop computers, cell phones, e-readers, andso-called tablets or slates, plug into an AC adapter that acts as apower supply and/or battery charger that converts the voltage of thecommercially available power to one the electronic device uses. Manyconsumers leave such chargers plugged in after the device's battery hasbeen charged, and even after the device is disconnected altogether.These idle chargers continue to consume energy even when they are nolonger providing any valuable function. Arguably, the power consumed byadapters is entirely wasted since it provides no functional value to theowner other than the convenience of leaving the adapter plugged in. TheEPA estimates that the power consumed by devices that are off or bychargers left plugged in amounts to approximately 45 billionkilowatt-hours of electricity per year and costs upwards of 3.5 billiondollars annually. Given these significant costs, the industry isfocusing on ways to reduce the power consumed by the electronic devicesthey manufacture.

BRIEF SUMMARY

According to one embodiment of the present invention, a method mayinclude detecting whether a connector element electrically connected toa direct-current output of a converter that converts alternating currentinto direct current is connected to an external device. The convertermay be disabled in response to the electrical connector component notbeing connected to the external device. In response to the electricalconnector component being connected to the external device, theconverter may be enabled.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In order that the advantages of the invention will be readilyunderstood, a more particular description of the invention brieflydescribed above will be rendered by reference to specific embodimentsthat are illustrated in the appended drawings. Understanding that thesedrawings depict only typical embodiments of the invention and are nottherefore to be considered to be limiting of its scope, the inventionwill be described and explained with additional specificity and detailthrough the use of the accompanying drawings, in which:

FIG. 1 is a block diagram showing the general operation of anillustrative converter system.

FIG. 2 is a generalized schematic diagram showing an illustrativeadapter system.

FIG. 3 is a schematic diagram showing an example of an illustrativeadapter system.

FIG. 4 is a schematic diagram showing another example of an illustrativeadapter system.

DETAILED DESCRIPTION

Referring now to FIG. 1, a converter system is generally shown at 10.Converter system 10 may include a converter 12, a connector assembly orsystem 14, and/or a control circuit 16. Converter 12 may be any suitablecircuit configured to convert from an input voltage V(IN), provided byan external electrical energy source, to an output voltage V(OUT), andmay include a control assembly 18. For example, converter 12 may beconfigured to convert from an alternating current (AC) input to a directcurrent (DC) output voltage, from an AC input of one voltage to an ACoutput of a different voltage, from a DC input of one voltage to a DCoutput of a different voltage, or from a DC input to an AC output.Control assembly 18 may include one or more electrical elementsconfigured to operate in a first mode enabling converter 12 to operate,or in a second mode disabling converter 12 from operating, in responseto a control signal. Control assembly 18 may enable and disable all orpartial operation of converter 12. For example, control assembly 18 mayinclude an in-line switch or other device that is operable toeffectively allow or impede current flow in an associated conductor.

Connector system 14 may be any suitable system for connecting converter12 to an external load or device 20, such as a mobile electronic devicehaving a rechargeable battery, or any electronic device requiring aninput voltage that is different than an available source voltage.

Control circuit 16 may be any suitable electrical and/or electroniccircuit operationally coupled to connector system 14 and configured tocontrol the operation of control assembly 18 based on a state of theconnector system by providing the control signal to the controlassembly. The control signal, in turn, may have two states. In responseto a first state of the control signal, control assembly 18 may enableoperation of converter 12, and in response to a second state of thecontrol signal, control assembly 18 may disable operation of converter12.

Referring now to FIG. 2, an example of converter system 10 is shown asan AC-to-DC adapter system 21 configured to convert an AC V(IN) to a DCV(OUT). In this example, adapter system 21 may include a converter 13,as an example of converter 12, a connector system 15 as an example ofconnector system 14, and a control circuit 16. Connector system 15provides a physical interface for electrically connecting externaldevice 20 (shown in FIG. 1) to converter 13. This physical interface mayinclude a first connector component 22 electrically connected toconverter 13 and configured to couple electrically and selectively witha second connector component 24, which may be electrically connected toexternal device 20. First connector component 22 may be manually ormechanically positioned in connection with second connector component,such as by inserting a plug into a receptacle. First connector component22 may be configured to achieve the functions described below and topresent a standard or preexisting interface for a conventional secondconnector component 24 of external device 20. The combination ofconnector components 22 and 24 may also be configured to provide theconnections described below. Connector components 22 and 24,individually or in combination, may also include electromechanical partsthat may be actuated by connection of connector components 22 and 24together. Many variations of the connector system are possible. Asuitable design may be selected based on a particular application.Accordingly, it will be seen that connector system 15 may be consideredto include connector components 22 and 24, whether or not the componentsare coupled.

First connector component 22 and second connector component 24 may takethe form of complementary or mating electrical connectors havingmultiple connector elements 26 attached to corresponding conductors.Connector elements 26 may be any suitable male or female members orelements configured to couple together to provide a secure electricalconnection. For example, connector elements 26 may include blades, pins,sheaths, conductors, contacts, or any other connector element well knownin the art. Connector components 22 and 24 may be configured as a plugand socket connector system. Connector components 22 and 24 may bekeyed, shielded, and/or coaxial. In some examples, connector system 14may include a four-pin or other plug and socket connection, coaxialpower connectors, barrel connectors, concentric barrel connectors,and/or tip connectors.

The topology generally depicted in FIGS. 2-4 is for flyback-styleadapters that may be used to provide power to laptops or mobileelectronic products. Other topologies are possible using the methods anddevices described herein, as may be appreciated by one having skill inthe art. As depicted, converter 13 may include a rectifier circuit 28.An input voltage V(IN) is generally input into rectifier circuit 28,which converts the alternating input voltage (AC) to direct voltage (DC)at the output of rectifier circuit 28. Rectifier circuit 28 may includewell-known components to rectify the voltage and to provideelectromagnetic interference filtering.

The rectified output of rectifier circuit 28 may be applied acrossprimary windings of a transformer 32 of a flyback converter subcircuit30. Flyback converter subcircuit 30 may include flyback transformer 32,a flyback switch 34, an in-line diode 36, and a capacitor 38.Application of the rectified voltage to transformer 32 may be controlledby control assembly 18. Control assembly 18 may include a pulse widthmodulator (PWM) 40 and a flyback switch 34 controlled by PWM 40.

Flyback switch 34 may be any suitable switching device configured to bedriven by a driving component such as PWM 40. For example, switch 34 maybe a semiconductor device such as a metal-oxide field effect transistor(MOSFET). Typical embodiments may utilize MOSFETs because of their highcommutation speed and high efficiency at low voltages. In otherexamples, switch 34 may include a bipolar junction transistor (BJT). PWM40 may be any electrical circuit configured to drive switch 34 at apredetermined switching frequency and/or duty cycle. PWM 40 may beembodied as an integrated circuit, and may be configured to accept oneor more inputs, for example from control circuit 16, in addition to oneor more outputs that communicate with switch 34.

Switch 34 may be driven by PWM 40 to repeatedly connect and disconnectthe rectified output of circuit 28 to transformer 32 at thepredetermined frequency. When switch 34 is closed, the primary windingsof transformer 32 experience an increase in magnetic flux as currentflows in the primary windings. However, transformer 32 is configuredsuch that in this condition, diode 36 in series with the secondarywindings of transformer 34 is reverse-biased and transformation isblocked. When switch 34 is opened, magnetic flux drops, and power istransferred to the secondary side of transformer 34 because diode 36 isnow forward-biased. This in turn supplies V(OUT) and charges capacitor38. When switch 34 is again closed, diode 36 is again reverse-biased andV(OUT) is supplied by capacitor 38. Because the output of this system iscontrollable by controlling the duty cycle, this rapidly-switching powersupply arrangement provides a tightly regulated output at V(OUT), andmay provide further functionality such as active power factorcorrection.

As depicted in FIG. 2, control circuit 16 may sense on a signal line 37a condition of connector system 14 and provide a signal to converter 13.Two nonexclusive options are shown. In a first example, a control signalmay be provided on a signal line 39 shown partially in dashed lines to acomponent of a control assembly, such as a switch, in rectifier circuit28. This control signal may act to cause the switch (not shown) to open,thus disabling circuit 28 and preventing operation of converter 13. Inother examples, a control signal is instead provided on a signal line 41to a control assembly 18, which includes PWM 40 and switch 34 and whichin turn acts to disable converter 13. For example, a control signal maybe provided to PWM 40, which responds by discontinuing the drivingsignal it provides to switch 34. Switch 34 may respond by remaining offor open, thus disabling converter 13.

Turning to FIG. 3, a more specific example of a converter system 10 oran adapter 21 is shown generally as an adapter system at 43. As isdescribed further below, adapter system 43 includes an example ofconverter 12 or 13, shown as a converter 35, a connector system 45 as anexample of a connector 14 or 15, and a control circuit 47 as an exampleof a control circuit 16.

In this example, connector system 45 includes a first connectorcomponent 48 having four elements 26, referred to as elements 26A, 26B,26C, and 26D. Element 26A may be electrically connected to a groundassociated with flyback converter subcircuit 30. Element 26D may beelectrically connected to the output voltage of converter 35. Elements26B and 26C may be electrically connected to components of controlcircuit 16. A second connector component 50 may include connectorelements 52, including connector elements 52A, 52B, 52C, and 52Dcorresponding one-for-one to respective ones of connector elements 26A,26B, 26C, and 26D. The connector elements 52A, 52B, and 52C may beshorted together such that coupling of the connector components resultsin electrical connection of elements 26A, 26B, and 26C, thus connectingall three to ground. In an embodiment where the connector elements arecoaxial or barrel connectors, connector elements 52A, 52B, and 52C maybe formed of a single barrel-shaped conductor that contacts connectorelements 26A, 26B, and 26C.

In this example, control circuit 47 may include an energy storage device54, such a battery 42, an electrical isolator 44, and a switch 56, suchas a transistor 46. Battery 42 may be a chargeable battery, and may beany suitable internal stored-power component. For example, battery 42may be a button cell or lithium-ion coin cell. In other examples, energystorage device 54 may include a capacitor.

Isolator 44 may be any suitable electronic component configured to becontrolled by one circuit while making or breaking a connection in asecond circuit electrically isolated from the first. Isolator 44 may bereferred to as a signal-generating element, because it generates asignal provided to control assembly 18. In some examples, controlcircuit 47 may include a connection-sensing circuit 58 couplingconnector component 48 to isolator 44 for producing the first controlsignal received from connector elements 26B and 26C and acontrol-signal-applying circuit 60 for applying the first control signalto control assembly 18 in response to receipt of the control signal fromthe connection-sensing circuit.

Isolator 44 may be an opto-isolator. Regardless of its specificimplementation, isolator 44 may further be considered to have a sourceside 44A and a controlling side 44B, where source side 44A is controlledby connection-sensing circuit 58 and controlling side 44B applies thecontrol signal to control-signal-applying circuit 60. Transistor 46 maybe any suitable switch configured to conduct between one pair ofterminals given an input signal on another pair of terminals, and, forexample, may be a bipolar-junction transistor having a base, acollector, and an emitter or a field-effect transistor having a source,a drain, and a gate.

In the example of FIG. 3, the negative terminal of battery 42 iselectrically connected to connector element 26B, and the base oftransistor 46 is electrically connected to connector element 26C througha resistor R1. The other terminals of transistor 46 are respectivelyconnected to the output voltage line at N1, and to the positive terminalof battery 42 at node N2 via a resistor R2. Source side 44A of isolator44 is electrically connected to node N2 through a resistor R3, and to alocal circuit ground. One conductor extending from controlling side 44Bof isolator 44 is electrically connected to rectifier circuit 28 and toPWM 40. For example, as shown, a ground conductor extending fromcontrolling side 44B may be connected to node N3, which in turn isconnected to the rectifier circuit 28 and PWM 40. Node N3 mayeffectively be a local circuit ground having the low or negative side ofthe rectified output voltage of rectifier circuit 28. A second conductorfrom the controlling side of isolator 44 is connected to a controllinginput of PWM 40, as shown.

When connector system 45 is in a connected state, connector elements 26Band 26C are connected to the local ground on the output side of theconverter, which connects the negative terminal of battery 42 to thelocal ground. This completes a circuit, causing a battery voltage onbattery 42 to power the source side 44A of isolator 44. This in turncauses the controlling side 44B to electrically connect the controllinginput terminal of PWM 40 and node N3, effectively shorting the circuitbetween the controlling input terminal and the ground terminal. Theground voltage on the controlling input terminal can be considered acontrol signal having a first state.

In this example, PWM 40 is configured to respond by providing a drivingsignal to switch 34, which enables converter 35 and provides converteroutput voltage V(OUT). With V(OUT) now provided at N1, and with the baseof transistor 46 connected to ground, current will flow throughtransistor 46 to node N2, which powers isolator 44 and also chargesbattery 42. Accordingly, as long as connector system 45 remains in aconnected state, converter 35 will continue to be operational.

Continuing with the example of FIG. 3, when connector system 45 isplaced in a disconnected state by uncoupling connector elements 26 and52, battery 42 and transistor 46 are disconnected from ground. Thisdenies isolator 44 of its source of power, causing it to no longerconnect node N3 to the controlling input terminal of PWM 40. The signalat the controlling input terminal of PWM 40 can now be said to be in asecond state. PWM 40 is configured to respond by discontinuing itsdriving signal to flyback switch 34, thereby opening the switch. Whenflyback switch 34 is open continuously, flyback converter subcircuit 30and thereby converter 35 are disabled. By this arrangement, power issaved by disabling converter 35 when converter system 21 is notconnected to external device 20.

FIG. 4 depicts yet another example of a converter system 10. In thisexample, a converter system 70 includes a converter 72, a connectorsystem 74, and a control circuit 76. The desired connection-dependentdisabling effect of the previous example may be obtained without usingan internal battery such as battery 42. Connector system 74, anotherexample of a connector system 14, may include first connector component78 and second connector component 80, each having respective connectorelements 82 and 84. Connector elements 82 include connector elements82A, 82B, and 82C. Connector elements 84 include connector elements 84A,84B, and 84C. Connector element 82A may be electrically connected to aground associated with flyback converter subcircuit 30, while connectorelement 82B is connected to the output voltage of converter 72, andconnector element 82C is connected to a component of control circuit 76.When connector component 80 is coupled to connector component 78,connector element 84A connects with connector element 82A, connectorelement 84B connects with connector element 82B, and connector element84C connects with connector element 82C.

In this example, a battery 86 of external device 20 may supply theelectromotive force to power isolator 44. In other words, when connectorsystem 74 is in a connected state, source side 44A of isolator 44 willbe electrically connected through resistor R3 to a positive terminal ofbattery 86 via connector elements 82C and 84C of connector system 74.The other terminal of battery 86 is grounded to a circuit ground of anoutput circuit of flyback converter subcircuit 30 via connector elements82A and 84A of the connector system. This completes a circuit and powersisolator 44. In similar fashion to the previous example shown in FIG. 3,one conductor of controlling side 44B is again connected to a groundterminal of PWM 40 via node N3 and the other conductor of isolatorcontrolling side 44B is connected directly to a control input terminalof PWM 40. As described with reference to converter 35 in FIG. 3, thecontrol signal applied to PWM 40 by isolator 44 has the samecorresponding effect of enabling and/or disabling converter 72 based onthe connection status of connector system 74.

It may be appreciated that battery 86 may not have sufficient reservecharge to power control circuit 76 as described. To remedy thissituation, a manually operable bypass switch 88 may be provided acrossthe lines connecting controlling side 44B of isolator 44 to the groundand control terminals of PWM 40. For example, a push-button bypassswitch 88 may be provided as shown in dotted line in FIG. 4. Shouldbattery 86 of the external device prove to be inadequately charged,switch 88 may be temporarily closed to connect the ground and controlterminals of PWM 40, thus manually providing a control signal to startswitching of flyback switch 34. This in turn results in an outputvoltage V(OUT), which is then applied to source side 44A of isolator 44through the connection of connector elements 82B and 84B, the electricalconnection of connector elements 84B and 84C in connector component 80,the connection of connector elements 82C and 84C, and resistor R3.

Returning now to FIG. 3, bypass switch 88 may also be included inconverter 43 as shown in dotted line. In the example of FIG. 3, a switchproviding manual operation may be desirable, for example, if battery 42is depleted or inoperable for some reason.

In other examples, not pictured in detail, isolator 44 controlsrectifier circuit 28, as discussed with reference to FIG. 2. With anotherwise similar arrangement to the various examples depicted in FIGS.3 and 4 and as represented by signal line 39 shown in dotted line andextending from control circuit 16. This control of circuit 28 may beaccomplished by placing controlling side 44B of isolator 44 in a currentcarrying conductor of circuit 28 such that the output of circuit 28 isinterrupted when isolator 44 does not have power. Alternatively,controlling side 44B of isolator 44 may control a disabling switch incircuit 28 or elsewhere in converter 14. In other words, placingconnector system 14 in a disconnected state by disconnecting theconnector components may deny isolator 44 its source of power by any ofthe means previously described. Instead of providing an input to PWM 40,isolator 44 (or control circuit 16 generally) may simply disconnect orotherwise interrupt the flow of current in another portion of thecircuitry of converter 12.

As discussed above with reference to FIG. 3, it may be appreciated thatin some examples, control circuit 16 may include a connection-sensingcircuit and a control-signal-applying circuit. For example, aconnection-sensing circuit 58 in the example shown in FIG. 3 may includebattery 42, transistor 56, and their associated connections andresistors. A control-signal-applying circuit 60 in this example mayinclude isolator 44 and associated connections at node N3 and PWM 40. Insome cases, source side 44A of isolator 44 may be included in aconnection-sensing circuit while controlling side 44B is included in acontrol-signal-applying circuit. In other examples, a connection-sensingcircuit extends into connector system 14.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the various embodiments of the present invention has beenpresented for purposes of illustration, but is not intended to beexhaustive or limited to the embodiments disclosed. Many modificationsand variations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

What is claimed is:
 1. A method comprising: detecting whether aconnector element electrically connected to a direct-current output of aconverter that converts alternating current into direct current isconnected to an external device; disabling the converter in response tothe connector element not being connected to the external device; andenabling the converter in response to manual operation of a bypassswitch configured to bypass a control circuit connected to a voltagesource when the connector element is connected to the external device.2. The method of claim 1, wherein disabling the converter includesapplying a control signal to a switch included in the converter.